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How Spindle Commands are Processed

The PathPilot® operating system sends a speed command (0 to 10 kHz on pin 1 of cable DB25) and a direction signal (pin 16) to the Machine Control Board. From the Machine Control Board, the PIC microcontroller:

  1. Reads the speed command.
  2. Determines the state of the Spindle Mode switch on the operator panel.

  3. Decides whether or not to send the 24 Vdc Run signal to the VFD.

    NOTE: If there is 24 Vdc, it sends a Run signal. If there is 0 Vdc, it sends a Stop signal.

  4. Decides whether or not to send the 24 Vdc Forward signal to the VFD.

    NOTE: If there is 24 Vdc, it sends a Forward signal. If there is 0 Vdc, it sends a Reverse signal.

  5. Translates the speed command (0 to 10 kHz) into an analog voltage (0 to 5V).

While this is in progress, the green Activity LED on the Machine Control Board flashes rapidly.

NOTE: The speed at which the green Activity LED flashes is proportional to the spindle speed command sent from PathPilot®.

Enable Commands

The VFD sends an enable signal to the Machine Control Board as 24 Vdc through wire J1-4 which is looped from terminals B2 to B4 on the VFD.

Run Commands

After PathPilot® signals a Run command to the Machine Control Board, the Machine Control Board returns 24 Vdc back to the VFD as a Run command through wire J1-3.

If rD displays in the VFD readout, the VFD is ready (enabled) but is not receiving a Run command on J1-3.

Forward Commands

After PathPilot® signals a Forward command to the Machine Control Board, the Machine Control Board returns 24 Vdc back to the VFD as a Forward command through wire J1-6.

If Fr -[NUMBER.NUMBER] displays in the VFD readout and the spindle only rotates in reverse, the VFD is not receiving a Forward command on J1-6.

Speed Commands

The Machine Control Board generates a 0 to 5V signal over wires J1-1 and J1-2, where J1-1 is for the speed command (Vdc proportional), and J1-2 is the ground (common) reference wire. These wires are connected from the J1 connector (located on the Machine Control Board) to terminals T1 and T2 on the VFD.

When the spindle is operating at full speed, the signal is 5V.

From the VFD readout, you can determine the following:

  • If Fr 0.0 displays, the VFD is receiving enable and run commands, but is not receiving a speed command. Fr [NUMBER].[NUMBER] indicates the spindle speed voltage frequency.
  • If iH displays in the VFD readout, the VFD is prevented from operating. Check the jumper connections between terminals B2 and B4 on the VFD.
  • If Tr displays in the VFD readout, the VFD circuit is open. Check motor connections, especially if a Quick-Change Motor Connection Kit is installed.